The Purcupile application relates to work reducing in which work-reducing rolls are subjected to high axial force by hydraulic-pressure means to suppress any tendency of the rolls to rotate relative to their arbor. It is an object of this invention to provide apparatus which shall effectively apply this high force, and which while having unique utility as part of work-reducing apparatus including reducing rolls has other uses and purposes.
In accordance with the teachings of the prior art (Hufnagl U.S. Pat. No. 3,793,869 and JETNUT hydraulic nuts sold by Jerry Tools Inc., 6206 Vine Street, Cincinnati, Ohio 45216) apparatus for applying high force hydraulically, specifically an hydraulic nut, is provided in which a piston or pad slideable in an annular cylinder is urged under hydraulic pressure into engagement with the object to which the force is to be applied. Typically the piston is sealed against leakage of the hydraulic fluid by an O-ring of neoprene or the like. This prior-art practice has not proved satisfactory because of the leakage of the hydraulic fluid and the deterioration of the O-ring gasket by the fluid, particularly at high temperature, typically above 200.degree. F to 300.degree. F.
It is an object of this invention to overcome the disadvantages of the prior art and to provide hydraulic pressure applying means without O-rings subjected directly to the hydraulic fluid and without experiencing leakage of the hydraulic fluid.